JP5548531B2 - Dual physical quantity sensor - Google Patents

Description

  The present invention relates to a dual physical quantity sensor.

  Patent Document 1 below discloses a dual pressure sensor that detects the pressure of an object to be measured by two pressure sensors, respectively. The dual pressure sensor of Patent Document 1 can be attached to a valve body of a flow control valve described in Patent Document 2 below and used as a differential pressure sensor, for example. In this case, the dual pressure sensor detects the fluid pressure upstream of the valve body and the fluid pressure downstream of the valve body, and outputs the detected fluid pressure to the flow rate measuring device that controls the flow control valve. The flow rate measuring device calculates the flow rate of the fluid flowing in the flow path of the flow rate control valve based on the differential pressure between the upstream fluid pressure and the downstream fluid pressure.

  By the way, some pressure sensors have a temperature characteristic in which an output value varies according to a temperature during use. In order to accurately calculate the fluid flow rate using a pressure sensor having such a temperature characteristic, it is necessary to accurately correct the temperature of the output value of the pressure sensor and to exclude the fluctuation due to temperature change from the output value. . For this reason, in Patent Document 1, temperature sensors are mounted on the two pressure sensors, and the detection values of the pressure sensors are corrected using the detected temperatures of the temperature sensors.

JP 2009-31003 A JP 2009-115302 A

  As described above, since the dual pressure sensor of Patent Document 1 needs to include two temperature sensors for one dual pressure sensor, it is difficult to meet the demands for reducing the number of parts and cost.

  Therefore, an object of the present invention is to provide a dual physical quantity sensor that can reduce the number of parts and cost.

  A dual physical quantity sensor according to the present invention includes a first physical quantity detection element that detects a physical quantity of a first measurement target, a second physical quantity detection element that detects a physical quantity of a second measurement target, a first physical quantity detection element, and a first physical quantity detection element, The temperature detection element for detecting the temperature of the two physical quantity detection elements and the correction for excluding the fluctuation due to the temperature change from the detection signal of the first physical quantity detection element are executed, and the corrected signal is used as the measurement signal for the first measurement target. And a first correction unit that outputs the correction signal, and a correction that excludes the fluctuation due to the temperature change from the detection signal of the second physical quantity detection element, and outputs the corrected signal as the measurement signal of the second measurement target. And a temperature detecting element integrated with the first physical quantity detecting element and the second physical quantity detecting element in contact with each other.

  With this configuration, one temperature detection element can be integrated in a state of being in contact with the first physical quantity detection element and the second physical quantity detection element. Therefore, the temperature of the first physical quantity detection element and the second physical quantity detection element Can be detected by one temperature detection element.

  The dual physical quantity sensor may further include a heat generator that equalizes the temperatures of the first physical quantity detection element and the second physical quantity detection element.

  As a result, even when the ambient temperature of the measurement target or the dual physical quantity sensor changes, the first physical quantity detection element and the second physical quantity detection element are brought to a level at which the influence of the temperature change can be eliminated by the heat generated by the heater. Since the temperature can be increased, the physical quantity detection accuracy can be improved.

  The dual physical quantity sensor may further include a heat generation control unit that controls a heat generation amount of the heat generator so that a temperature detected by the temperature detection element becomes a predetermined temperature.

  Thereby, for example, it is possible to suppress the amount of heat generated by the heater so that the temperature does not rise to a temperature at which the first physical quantity detection element and the second physical quantity detection element are damaged.

  ADVANTAGE OF THE INVENTION According to this invention, the dual physical quantity sensor which can reduce a number of parts and cost can be provided.

It is a half sectional view of the dual pressure sensor in an embodiment. It is the II-II arrow direction sectional view shown in FIG. It is a functional lineblock diagram of the dual pressure sensor in an embodiment. It is a functional lineblock diagram of the dual pressure sensor in the 1st modification. It is a functional lineblock diagram of the dual pressure sensor in the 2nd modification. It is a functional block diagram of the dual pressure sensor in a 3rd modification.

  An embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

  In the present embodiment, for example, a dual pressure sensor having two pressure sensors will be described as the dual physical quantity sensor. The physical quantity is not limited to pressure, and can be applied to other physical quantities as well.

  FIG. 1 is a half sectional view of a dual pressure sensor 1 according to the embodiment, and FIG. 2 is a sectional view taken along the line II-II in FIG. The dual pressure sensor 1 includes an airtight container 2, two pressure sensors 3 </ b> A and 3 </ b> B, a temperature sensor 4, a heater 5, a substrate 6, and a control circuit 7.

  The airtight container 2 has a container body 21 and a lid body 22 formed of synthetic resin or the like. In the following description, in the airtight container 2, the side where the lid body 22 is located is the upper side, and the side where the container body 21 is located is the lower side. The container body 21 is a bottomed box-type container that opens upward. In the bottom plate of the container main body 21, through holes 21h are formed corresponding to the two pressure sensors 3A and 3B, respectively. The lid 22 is screwed and fixed to the upper surface of the container main body 21 via a seal member (not shown), thereby hermetically sealing the opening of the container main body 21.

  Inside the container body 21, two pressure sensors 3A and 3B are arranged in close contact with each other, and a temperature sensor 4 is provided on the upper surface of the pressure sensors 3A and 3B. The pressure sensors 3A and 3B and the temperature sensor 4 are integrated in a state where they are in contact with each other. As described above, by keeping the two pressure sensors 3A and 3B in close contact with each other, a temperature difference between the pressure sensors 3A and 3B can be hardly generated.

  The pressure sensors 3A and 3B detect the pressure of the measurement target taken in from the respective introduction holes 3h. For example, a fluid such as water or gas corresponds to the measurement target. The pressure sensors 3A and 3B include, for example, a semiconductor substrate (silicon) on which a diaphragm (thin pressure sensing portion) is formed and a diffusion type strain gauge formed on the semiconductor substrate by an impurity or ion implantation technique. This corresponds to the semiconductor pressure sensor. The diffusion type strain gauge detects the strain due to the pressure to be measured of the diaphragm using the piezoresistive effect and converts it into an electric signal. Each of the pressure sensors 3A and 3B has a temperature characteristic that an output gain or offset changes according to the operating temperature.

  The temperature sensor 4 detects the temperature of the pressure sensors 3A and 3B. The heater 5 warms the surroundings of the pressure sensors 3A and 3B uniformly at a predetermined temperature. The predetermined temperature is preferably set to a temperature slightly higher than the upper limit of the temperature range that can be taken by the object to be measured. For example, when the temperature range that can be taken by the object to be measured is 7 ° C. to 65 ° C., the temperature is set to about 70 ° C. to 75 ° C. that is slightly higher than the upper limit of 65 ° C. Thereby, even when the ambient temperature of the object to be measured or the dual pressure sensor is changed due to a change in the outside air temperature or the like, the pressure sensor 3A, 3B can reach a level at which the influence of the temperature change can be eliminated by the heat generation of the heater 5. Since temperature can be raised, the situation where a temperature difference arises between pressure sensor 3A, 3B can be suppressed. Therefore, the pressure value detection accuracy can be improved.

  The control circuit 7 is provided on the substrate 6 and controls the operation of each part of the dual pressure sensor 1. The control circuit 7 realizes each function of the dual pressure sensor 1 described below. With reference to FIG. 3, the functional configuration of the dual pressure sensor 1 in the embodiment will be described.

  As shown in FIG. 3, the dual pressure sensor 1 includes a heater unit 71, a first pressure detection unit 72A, a second pressure detection unit 72B, a temperature detection unit 73, a first correction unit 74A, and a second correction. Part 74B. FIG. 3 shows a configuration example in the case where a flow rate measuring device 100 that measures the flow rate of the fluid is provided in the subsequent stage of the dual pressure sensor 1.

  The heater unit 71 drives the heater 5 to warm the pressure sensors 3A and 3B to a predetermined temperature.

  The first pressure detection unit 72A acquires a detection signal from the pressure sensor 3A, and outputs the acquired detection signal to the first correction unit 74A. The second pressure detection unit 72B acquires the detection signal from the pressure sensor 3B, and outputs the acquired detection signal to the second correction unit 74B.

  The temperature detection unit 73 acquires the detection temperature from the temperature sensor 4 and outputs the acquired detection temperature to the first correction unit 74A and the second correction unit 74B.

  The first correction unit 74A corrects the detection signal acquired from the first pressure detection unit 72A based on the detected temperature acquired from the temperature detection unit 73, and uses the corrected signal as the first measurement signal in the flow measurement device 100. Output. The second correction unit 74B corrects the detection signal acquired from the second pressure detection unit 72B based on the detected temperature acquired from the temperature detection unit 73, and uses the corrected signal as the second measurement signal in the flow measurement device 100. Output.

  The first correction unit 74A and the second correction unit 74B include selector units A1 and B1, A / D conversion units A2 and B2, correction calculation units A3 and B3, and correction formula storage units A4 and B4, respectively. The selector units A1 and B1 are, for example, multiplexers, which receive signals from the first pressure detection unit 72A or the second pressure detection unit 72B and the temperature detection unit 73, respectively, and select one of the signals to perform A / D It outputs to conversion part A2, B2.

  The A / D conversion units A2 and B2 convert the analog signals received from the selector units A1 and B1 into digital signals and output the digital signals to the correction calculation units A3 and B3. The correction calculation units A3 and B3 execute a correction process on the pressure values corresponding to the digital signals received from the A / D conversion units A2 and B2 using the correction formulas stored in the correction formula storage units A4 and B4. Then, a signal corresponding to the pressure value after the correction processing is output to the flow measuring device 100 as a measurement signal. As the correction formula, for example, a primary formula or a quadratic formula using temperature as a variable can be used. As the correction formula, for example, an experiment or the like is performed in advance to obtain a pressure value variation due to a temperature change from the reference temperature for each temperature, and a formula is prepared so that this variation can be excluded from the detection signal. That is, the correction process is a process for performing correction to exclude the variation due to the temperature change from the detection signal of the first pressure detection unit 72A or the second pressure detection unit 72B.

  The flow measurement device 100 obtains a difference between the first measurement signal output from the first correction unit 74A and the second measurement signal output from the second correction unit 74B, thereby obtaining a difference between the pressure sensors 3A and 3B. Calculate the pressure. This differential pressure can be used as follows, for example, when the dual pressure sensor 1 is attached to the valve body of the flow control valve. In this case, the pressure sensor 3A and the pressure sensor 3B are arranged so that the fluid pressure on the upstream side and the fluid pressure on the downstream side of the valve body can be measured, respectively.

  The flow rate Q of the fluid flowing in the flow path of the flow control valve is a flow coefficient (Cv value) determined by the pressure difference ΔP of the fluid between the upstream flow path and the downstream flow path of the valve body and the opening of the valve body. ) And the following equation (1). In the following formula (1), A is a constant.

  Q = A * Cv * √ΔP (1)

  That is, the flow rate Q of the fluid can be calculated by substituting the differential pressure calculated by the flow rate measuring device 100 into ΔP in the above equation (1), and the opening degree of the valve body is controlled according to the flow rate Q. be able to.

  When the dual pressure sensor 1 is attached to the flow control valve, the dual pressure sensor 1 and the flow measuring device 100 operate as follows, for example.

  First, when the pressure to be measured upstream of the valve body is applied to the diaphragm of the pressure sensor 3A and the pressure to be measured downstream of the valve body is applied to the diaphragm of the pressure sensor 3B, each pressure sensor 3A, 3B The diaphragm is distorted according to the applied pressure, and the output voltage of the diffusion strain gauge changes due to this distortion.

  Subsequently, the first pressure detection unit 72A and the second pressure detection unit 72A measure the respective pressures based on changes in the output voltage, and use the measurement results as detection signals for the first correction unit 74A or the second correction unit 74B. Output. In this case, since the pressure in the hermetic container 2 is applied as a reference pressure to the diaphragm, the output voltage of each pressure sensor 3A, 3B becomes an output voltage of an absolute pressure corresponding to each measured pressure.

  Subsequently, the first correction unit 74A and the second correction unit 74B each execute the correction process of the pressure value corresponding to the detection signal using the detected temperature acquired from the temperature detection unit 73, and the execution result is measured signal. Are respectively output to the flow rate measuring device 100.

  Subsequently, the flow measuring device 100 calculates a differential pressure ΔP using a pressure value corresponding to each measurement signal received from the dual pressure sensor 1, and calculates the differential pressure ΔP by substituting the calculated differential pressure ΔP into the above equation (1). By doing so, the flow rate Q of the fluid flowing through the flow rate control valve is calculated.

  As described above, according to the dual pressure sensor of the present embodiment, the temperature sensor 4 can be integrated with the pressure sensors 3A and 3B in contact with each other. It is possible to detect with one temperature sensor 4.

[Modification]
Although the present invention has been described by using the above-described embodiments, the description and drawings constituting a part of this disclosure do not limit the present invention. From this disclosure, various alternative embodiments and operational techniques should be apparent to those skilled in the art.

  For example, in the embodiment described above, the heater 5 is provided, but the heater 5 may be omitted. FIG. 4 shows a functional configuration of the dual pressure sensor 1 in the first modification. As shown in FIG. 4, the dual pressure sensor 1 in the first modification is different from the dual pressure sensor 1 in the above embodiment in that the heater unit 71 in the embodiment shown in FIG. 3 is not included.

  In the embodiment described above, the amount of heat generated by the heater 5 is not controlled, but the heater 5 is detected using the temperature detected by the temperature detection unit 73 so that the temperature of the pressure sensors 3A and 3B is maintained at a predetermined temperature. It is good also as carrying out feedback control of the emitted-heat amount. FIG. 5 shows a functional configuration of the dual pressure sensor 1 in the second modification. As shown in FIG. 5, the dual pressure sensor 1 in the second modified example is different from the dual pressure sensor 1 in the above embodiment in that it further includes a heater control unit 75 in addition to each part in the embodiment shown in FIG. 3. The heater control unit 75 controls the amount of heat generated by the heater 5 so that the temperature detected by the temperature detection unit 73 becomes a predetermined temperature set in advance. Thereby, for example, the amount of heat generated by the heater 5 can be suppressed so that the pressure sensors 3A and 3B do not rise to a temperature at which they are damaged.

  When feedback control is performed on the amount of heat generated by the heater 5 in the second modification, the temperature of the pressure sensors 3A and 3B is maintained at a predetermined temperature. As a result, the correction equation used when correcting the pressure values of the pressure sensors 3A and 3B The variable will also be maintained at a predetermined temperature. Therefore, in this case, the pressure value may be corrected using a correction formula in which the variable is fixed at a predetermined temperature. FIG. 6 shows a functional configuration of the dual pressure sensor 1 in the third modification. As shown in FIG. 6, the dual pressure sensor 1 in the third modified example further includes a heater control unit 75 in addition to each unit in the embodiment shown in FIG. 3, and detects the temperature detected by the temperature detection unit 73 as the first correction unit 74 </ b> A. And the point which does not input into the 2nd correction | amendment part 74B differs from the dual pressure sensor 1 in the said embodiment. The heater control unit 75 controls the amount of heat generated by the heater 5 so that the temperature detected by the temperature detection unit 73 becomes a predetermined temperature set in advance as in the second modification. In addition, a predetermined temperature is set in advance as a variable of the correction formula stored in the correction formula storage units A4 and B4. Thereby, since the correction formula can be simplified, the storage area of the correction formula can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Dual pressure sensor, 2 ... Airtight container, 3A, 3B ... Pressure sensor, 3h ... Introduction hole, 4 ... Temperature sensor, 5 ... Heater, 6 ... Substrate, 7 ... Control circuit, 21 ... Container body, 21h ... Insertion hole 22 ... Lid, 71 ... Heater, 72A ... First pressure detector, 72B ... Second pressure detector, 73 ... Temperature detector, 74A ... First corrector, 74B ... Second corrector, 75 ... Heater Control unit, 100 ... flow rate measuring device, A1, B1 ... selector unit, A2, B2 ... A / D conversion unit, A3, B3 ... correction calculation unit, A4, B4 ... correction formula storage unit.

Claims (4)

A first physical quantity detection element for detecting a physical quantity of the first measurement target;
A second physical quantity detection element for detecting a physical quantity of the second object to be measured;
A temperature detection element for detecting temperatures of the first physical quantity detection element and the second physical quantity detection element;
A first correction unit that performs a correction that excludes a variation due to a temperature change from the detection signal of the first physical quantity detection element, and outputs the corrected signal as a measurement signal of the first measurement target;
A second correction unit that performs correction to exclude a variation due to temperature change from the detection signal of the second physical quantity detection element, and outputs the corrected signal as a measurement signal of the second measurement target;
A heater that surrounds a part of the first physical quantity detection element and the second physical quantity detection element without interruption, and equalizes the temperatures of the first physical quantity detection element and the second physical quantity detection element ,
The first physical quantity detection element and the second physical quantity detection element are provided in close contact with each other,
The dual physical quantity sensor, wherein the temperature detection element is integrated with both the first physical quantity detection element and the second physical quantity detection element in contact with each other. Dual physical quantity sensor according to claim 1, wherein the heat generation control section for controlling the heating value of the heat generator so that the detected temperature becomes a predetermined temperature predetermined by the temperature detection element further comprises. 3. The dual physical quantity sensor according to claim 1, wherein the first correction unit and the second correction unit perform the correction using a temperature detected by the temperature detection element. The dual physical quantity sensor according to claim 2, wherein the first correction unit and the second correction unit perform the correction using the predetermined temperature.

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